(a) Field of the Invention
This invention relates to a process for preparing (4-pyridinylmethyl) lower alkyl ketones and (4-pyridinylmethyl) aryl ketones and to intermediates useful in such process.
Generally, compounds of the type described herein are useful as intermediates in the preparation of pharmaceutically active 1,2-dihydro-6-R-2-oxo-5-pyridinyl compounds having cardiotonic activity and related such compounds.
(b) Description of the Prior Art
The 4-pyridinylmethyl lower alkyl ketones are generally known compounds which are prepared by known methods; i.e. Rec. Trav. Chim. 72,522 (1953); U.S. Pat. No. 3,133,077 (May 12, 1964), Bull Soc Chim 1968, 4132; Chem Abs 79,8539h (1973); Chem Abstrs. 81, 120 401a (1974); J. Org. Chem 39, 3834 (1974); Chem Abstrs. 87, 6594q, (1977); J. Org Chem 43, 2286 (1978), J Org Chem 22, 939 (1957); U.S. Pat. No. 4,312,875 (Jan. 26, 1982).
All of the preceeding methods describe the synthesis of 2- and 4-pyridinylmethyl alkyl ketones and/or 2- and 4-pyridinylmethyl aryl ketones through acylation of 2-, or 4-pyridinylmethyl anions. A large variety of bases, solvents and acyl equivalents have been used. Few of the methods give high yields and most involve air and moisture sensitive, flammable bases in flammable and expensive etheral solvents and often require exhaustive isolation procedures.